Fire Resistance of Wood Joist Floor Assemblies

This paper discusses the factors that affect the fire resistance performance of lightweight wood frame unrestrained floor assemblies protected with Type X gypsum board ceiling finishes. Twenty-two fire resistance experiments were conducted on full-scale load-bearing wood joist floor assemblies using the ULC standard fire exposure time–temperature curve that is similar to ASTM E119 standard. Parameters investigated in this study include the effects of gypsum board screws spacing from board edges, insulation installation, insulation type, joist spacing for assemblies with gypsum board attached to resilient channels, joist depth, resilient channel installation, resilient channel spacing, sub-floor topping, number of sub-floor layers, and load magnitude. The impact of these parameters on the fire resistance of wood joist frame floor assemblies is discussed. The fire resistance of wood frame floors appears essentially to be governed by the gypsum board screw spacing from the board edges and the type of insulation in assemblies with one layer of gypsum board and by the resilient channel spacing and the gypsum board screw spacing from the board edges in assemblies with two layers of gypsum board. The effects of other parameters in assemblies with two layers of gypsum board such as the joist spacing where the gypsum boards are attached to resilient channels, installation of resilient channels, insulation installation, insulation type, adding gyp-crete topping above the sub-floor and number of sub-floor layers on fire resistance are relatively insignificant.     

Factors Influencing Fire Resistance of Load-bearing Steel Stud Walls

This paper presents the effect of various factors on the fire resistance of load-bearing, gypsum board protected, steel stud wall assemblies. A detailed experimental study was conducted to evaluate the fire resistance of 14 full-scale steel stud wall assemblies. Both single row and double row steel stud configurations with installation of gypsum board on each of the exposed and unexposed sides, and with and without insulation in the cavity, were considered in the experimental program. The insulation used were glass, rock and dry blown cellulose fibers. Data from the experimental program are used to determine the effects of stud-spacing, shear membrane, load intensity, resilient channel installation, insulation type and gauge thickness of studs on the fire resistance of gypsum board-protected, steel stud wall assemblies. Results from the studies show that the insulation type and number of gypsum board layers have significant influence on the fire resistance of steel stud wall assemblies. Prior to August 2005, he was a Senior Research Officer at the Institute for Research in Construction, National Research Council of Canada.     

Light-Weight Frame Wall Assemblies: Parameters for Consideration in Fire Resistance Performance-Based Design

With the advent of performance-based codes and fire safety design options, it is essential to determine parameters that affect the fire-resistance performance of assemblies. This paper presents the results of 17 full-scale fire-resistance tests conducted as part of a major industry-government research program investigating parameters that affect the fire-resistance performance of light-weight frame wall assemblies. These include the effects of insulation type, insulation width between studs, resilient channel location, gypsum board thickness, number of gypsum board layers, glass fiber in the gypsum board core, gypsum board mass per unit area, and stud type for light-weight frame wall assemblies finished with gypsum board. The effects of these parameters on the fire resistance are discussed.     

Fire Resistance of Loadbearing Steel-Stud Wall Protected with Gypsum Board: A Review

With the increased use of cold-formed lightweight steel framing (LSF), there is growing demand for the proper assessment of its performance in building fires. In partnership with the North American steel industry, the National Research Council of Canada (NRC) is conducting an experimental and analytical study on the fire resistance of loadbearing cold-formed steel-framed wall and floor assemblies. As part of this collaboration, this literature survey summarizes the information available on the topics related to the fire resistance of loadbearing cold-formed steel-stud walls clad with gypsum board. The current practice of establishing their fire-resistance rating, based on full-scale furnace tests, is assessed. Previous experimental and analytical studies on the subject and on the thermal and mechanical properties of the constituent materials—steel, gypsum board, and insulation—at elevated temperatures are also discussed. Future research needs are identified in the context of recent performance-based fire safety engineering concepts.     

Fire resistance of LSF floors made of hollow flange channels

Light gauge Steel Frame (LSF) floor systems are generally made of conventional lipped channel section (LCS) joists and lined using fire resistive gypsum boards. Although the use of LSF floor systems has significantly increased in the construction of fire rated buildings, it is limited to those made of LCS joists. Since the fire resistance ratings (FRR) for steel sections other than LCS joists are not available, engineers are reluctant to use innovative steel joists in LSF floor systems exposed to fire conditions. To overcome these limitations, a new LSF floor system recently developed using a welded hollow flange channel (HFC) section as joists was investigated using both experimental and numerical studies under standard fire conditions. Both these studies demonstrated higher fire resistance ratings in comparison to those made of LCS joists. However, they were limited to one welded HFC joist section. Hence a detailed parametric study of LSF floor systems made of HFC joists was undertaken to investigate the effects of joist sizes and shapes, steel types and service openings on the FRR using the validated finite element models. This paper presents the details of this finite element analysis based parametric study and the load ratio versus time curves. These results can be used in designing the LSF floors made of HFC joists with varying sizes for different industry applications without the use of expensive fire tests.     

Fire performance of cold-formed steel wall panels and prediction of their fire resistance rating

Recent research at the Queensland University of Technology has investigated the structural and thermal behaviour of load bearing Light gauge Steel Frame (LSF) wall systems made of 1.15 mm G500 steel studs and varying plasterboard and insulation configurations (cavity and external insulation) using full scale fire tests. Suitable finite element models of LSF walls were then developed and validated by comparing with test results. In this study, the validated finite element models of LSF wall panels subject to standard fire conditions were used in a detailed parametric study to investigate the effects of important parameters such as steel grade and thickness, plasterboard screw spacing, plasterboard lateral restraint, insulation materials and load ratio on their performance under standard fire conditions. Suitable equations were proposed to predict the time–temperature profiles of LSF wall studs with eight different plasterboard-insulation configurations, and used in the finite element analyses. Finite element parametric studies produced extensive fire performance data for the LSF wall panels in the form of load ratio versus time and critical hot flange (failure) temperature curves for eight wall configurations. This data demonstrated the superior fire performance of externally insulated LSF wall panels made of different steel grades and thicknesses. It also led to the development of a set of equations to predict the important relationship between the load ratio and the critical hot flange temperature of LSF wall studs. Finally this paper proposes a simplified method to predict the fire resistance rating of LSF walls based on the two proposed set of equations for the load ratio–hot flange temperature and the time–temperature relationships.     

Thermal Performance of Composite Panels Under Fire Conditions Using Numerical Studies: Plasterboards, Rockwool, Glass Fibre and Cellulose Insulations

In recent times, light gauge steel frame (LSF) wall systems are increasingly used in the building industry. They are usually made of cold-formed and thin-walled steel studs that are fire-protected by two layers of plasterboard on both sides. A composite LSF wall panel system was developed recently, where an insulation layer was used externally between the two plasterboards to improve the fire performance of LSF wall panels. In this research, finite element thermal models of the new composite panels were developed using a finite element program, SAFIR, to simulate their thermal performance under both standard and Eurocode design fire curves. Suitable apparent thermal properties of both the gypsum plasterboard and insulation materials were proposed and used in the numerical models. The developed models were then validated by comparing their results with available standard fire test results of composite panels. This paper presents the details of the finite element models of composite panels, the thermal analysis results in the form of time–temperature profiles under standard and Eurocode design fire curves and their comparisons with fire test results. Effects of using rockwool, glass fibre and cellulose fibre insulations with varying thickness and density were also investigated, and the results are presented in this paper. The results show that the use of composite panels in LSF wall systems will improve their fire rating, and that Eurocode design fires are likely to cause severe damage to LSF walls than standard fires.     

Fire tests of Magnesium Oxide board lined light gauge steel frame wall systems

Recently, Magnesium Oxide (MgO) board has been widely used in LSF wall systems because of its improved acoustic properties, impact resistance, structural strength and serviceability. However, their thermal properties and fire performance have not been fully investigated. Therefore, in this research study thermal properties of two different types of MgO boards available in Australia were measured and their fire performance was investigated using three full-scale fire tests of LSF walls lined with two types of MgO board. Although the tests were conducted on two different types of MgO boards with different configurations, the fire test results gave a fire resistance level (FRL) of 30 min, in which the failure was initiated by integrity of the board with either board cracking or board joint opening. This paper presents the details of the thermal property tests and the three full-scale fire tests, and their results. In addition, the effects of different MgO boards, joint configurations and compounds, noggings, screw fastening techniques and cavity insulation on the fire performance of LSF walls are also presented.     

竹结构轻型框架房屋火灾安全性能试验研究

采用欧洲规范确定房屋的火灾荷载后,使用木垛火作为火源,对一足尺竹结构轻型框架房屋进行火灾模拟试验,研究了此类型房屋的火灾安全性能。历时1h的火灾作用后,墙体骨柱在9.5mm厚普通石膏板的保护下,平均炭化深度仅为截面尺寸的1/3,而楼盖格栅在19mm厚防火石膏板的保护下几乎没有火灾损伤,房屋最终保持了良好的结构整体性,表明此类竹结构房屋耐火时间可以达到1.0h以上,具有良好的火灾安全性能;墙体和楼板内外表面的热电偶数据显示迎火面墙体最高温度达到686℃的情况下,背火面温度维持在一个较低的温度水平(最高温度仅为46～84℃),表明采用石膏板和岩棉的房屋墙体和楼板具有良好的保温隔热性能;在试验研究的基础上,对竹结构轻型框架房屋的构造措施提出了设计建议。     

Full-scale fire experiments on load-bearing cold-formed steel walls lined with different panels

Cold-formed steel (CFS) wall systems were increasingly used as primary load-bearing structural components in residential and industrial buildings. Previous studies were mainly to investigate the fire performance of non-load bearing CFS wall systems lined with gypsum plasterboards. In order to improve the fire performance of load-bearing CFS wall systems more efficiently, this paper presented a detailed experimental investigation on five full-scale CFS walls lined with double layers of three different fire resistant panels on both sides, including fire-resistant gypsum plasterboard, bolivian magnesium board and calcium silicate board. The results showed a noticeable disadvantage of the calcium silicate board due to explosive spalling at high temperatures, and this might cause severe safety issues in an actual fire situation. For CFS walls lined with gypsum plasterboard as the face layer and bolivian magnesium board as the base layer on both sides, different load ratios may result in different failure modes, and the fire resistance time would be more than 90 min when the load ratio was less than 0.65. It was also demonstrated that the fire performance of bolivian magnesium board was superior to that of the fire resistant gypsum plasterboard, therefore the former may be recommended to be used in CFS structures to replace gypsum plasterboards as the base layer.     

岩棉保温装饰一体板在钢边框复合轻质板中的应用研究

探讨一种适用于钢结构装配式住宅的外墙外保温体系的组成、岩棉保温装饰一体板与钢边框复合轻质板的连接方式、外墙外保温体系的系统试验等。该外墙外保温体系具有保温效果好、防火性能优异、体系连接安全、施工效率高等优点,具有广阔的应用前景。     

钢结构围护-防火一体化材料耐火性能试验研究

根据钢结构防火保护材料的相关技术要求,通过对常见的钢结构围护材料进行评价,筛选了包括水泥基材料中的无机轻集料砂浆、胶粉聚苯颗粒、蒸压轻质加气混凝土(autoclaved lightweight concrete,ALC),保温浆料中的石膏基保温浆料、微孔硅酸钙浆料,以及保温板材中的发泡陶瓷保温板和岩棉板在内的3类可以兼...     

岩棉板外墙外保温防火结构的创新应用

为了提高建筑外墙外保温围护结构的防火性,使得外保温围护结构能够与墙体具有防火等级相同、耐久性与墙体使用寿命相同,选用岩棉板外墙外保温防火结构系统,采用先进的岩棉板加钢丝网锚固技术、保温层抗裂技术、内外层一体化设计及施工技术,成功地应用在具体工程中,通过竣工后检测,其传热系数、耐候性指标均达到了相关标准规定的要求,可为同类工程提供参考。     

发泡陶瓷保温板外保温系统建筑应用与质量控制

外墙外保温系统的防火性能、耐久性能已备受业内重视。发泡陶瓷保温板是一种新型的防火、保温材料,用于外墙外保温系统可大大提高系统的防火、耐久性能。对该保温材料及其外保温系统、防火隔离带构造进行了研究和试点应用,结果表明该技术防火性能佳、与建筑同寿命、施工便捷、质量通病少,具有广阔的应用前景。详述了其施工和质量控制要点。     

Development of realistic design fire time-temperature curves for the testing of cold-formed steel wall systems

Fire resistance rating of light gauge steel frame (LSF) wall systems is obtained from fire tests based on the standard fire time-temperature curve. However, fire severity has increased in modern buildings due to higher fuel loads as a result of modern furniture and light weight constructions that make use of thermoplastics materials, synthetic foams and fabrics. Some of these materials are high in calorific values and increase both the spread of fire growth and heat release rate, thus increasing the fire severity beyond that of the standard fire curve. Further, the standard fire curve does not include a decay phase that is present in natural fires. Despite the increasing usage of LSF walls, their behavior in real building fires is not fully understood. This paper presents the details of a research study aimed at developing realistic design fire curves for use in the fire tests of LSF walls. It includes a review of the characteristics of building fires, previously developed fire time-temperature curves, computer models and available parametric equations. The paper highlights that real building fire time-temperature curves depend on the fuel load representing the combustible building contents, ventilation openings and thermal properties of wall lining materials, and provides suitable values of many required parameters including fuel loads in residential buildings. Finally, realistic design fire time-temperature curves simulating the fire conditions in modern residential buildings are proposed for the testing of LSF walls.     

CFRP加固钢筋混凝土梁耐火性能试验研究

采用厚型防火涂料和硅酸钙防火板对3根CFRP加固钢筋混凝土梁进行了不同方法的防火保护,在ISO834标准升温条件下进行耐火性能对比试验。分析了不同防火方法及端部锚固性能对高温下CFRP加固梁的温度场变化规律、跨中挠度、破坏形态及耐火极限的影响。试验研究表明:采用50mm厚防火涂料和40mm硅酸钙防火板对加固梁进行三面U型防火保护,耐火极限均可达到2.0h;提高CFRP的端部锚固性能可有效地改善加固梁的耐火性能;防火涂层中增设钢丝网片约束防火涂料、防止开裂和脱落效果明显。试验结果分析表明:CFRP加固混凝土梁防火保护的重点并非是CFRP材料本身,而是钢筋混凝土梁;可以通过延缓钢筋与混凝土材料的温度增长来推迟加固梁达到极限状态的时间,从而获得较好的耐火性能。     

Shear capacity of cold-formed light-gauge steel framed shear-wall panels with fiber cement board sheathing

Being light in weight, cold-formed steel shear wall panels (SWPs) made with light gauge steel are extensively used in residential and office buildings (low to mid-rise), particularly in structures under seismic loadings. Many design practices involve the use of fiber cement board (FCB) as sheathing material both for hollow and infilled walls. FCB is a preferred choice as cladding material due to many advantages it provides such as water resistance, lower cost, withstand temperature variation, resistance to humidity and termite attack, better acoustic insulation, and superior fire resistance properties. In the absence of design guidelines, based on cold-formed light gauge steel shear walls with FCB sheathing, the designers resolve to use the guideline available for gypsum wall board (GWB) and fiberboard (FB) available in American Iron and Steel Institute Lateral Design. As a pioneer study, an experimental program was designed to investigate the behavior of cold-formed light gauge steel shear walls, both hollow and infilled with expanded polystyrene (EPS) foam concrete, with FCB sheathing on both sides under monotonic loading. The tests were performed according to ASTM E564 standard. Results show that the strength of shear walls with FCB sheathing is much higher than GWB and FB sheathing, suggesting that substitute design practices are highly conservative. Test results can help designers choose desired lateral stiffness and load carrying capacity of light gauge steel SWPs more efficiently, by selecting appropriate framing, infill, and sheathing material.     

A model for predicting heat transfer through noninsulated unloaded steel-stud gypsum board wall assemblies exposed to fire

With the advent of performance-based codes and performance-based fire safety design options, validated fire-resistance models have become essential. In this paper, a one-dimensional heat transfer model for steel-stud, noninsulated, unloaded gypsum board protected wall assemblies is presented. Also presented are a comparison between temperature predictions and measured temperatures at different locations in gypsum board wall assemblies as well as a comparison between the predicted and measured fire-resistance ratings. The model, which predicts slightly conservative fire-resistance ratings compared to the experimental measurements, is appropriate for most fire safety engineering applications. Considerations for further model development are identified.     

多层轻钢结构商品住宅的设计与施工

介绍了多层轻钢结构住宅的建筑和结构设计,包括围护材料选用,屋、楼面的选取,防火设计等,主体结构的选择与设计,钢结构的防火防腐处理以及砌体与钢梁柱处的防裂处理等。